Various methods and apparatus for producing lasers are known in the art. For example, the Lempicki U.S. Pat. No. 4,797,889 discloses a solid state laser in which molecules containing transition metal ions form the lasing medium. In one embodiment, a molecule containing molybdenum in combination with either oxygen or a halogen atom is employed and lasing occurs at 450 nm. The Yang et al. U.S. Pat. No. 4,132,962 discloses a solid state laser in which the lasing medium consists of neutral atoms in a crystal environment. The Liu et al. U.S. Pat. No. 4,426,706 discloses an excimer laser in which the discharge tube contains electrodes made of molybdenum. The lasing process is based on a rare-gas halide such as krypton fluoride. The Jaegle et al. U.S. Pat. No. 3,826,996 discloses a laser system employing a collisionally excited plasma in which the upper levels of the lasing transitions are populated by a recombination process. The plasma is formed by use of a laser focused onto a target material.
The Bramley U.S. Pat. No. 3,493,845 discloses a system in which microwave radiation is employed to excite a lasing gas medium comprising an atom with a metastable level as the lowest excited level. The microwave radiation is used to both pump the ion to its metastable level directly from its ground state and to quench other excited states of the atom so as to produce a population inversion. The lasing transitions of this system are those of a neutral atom. The White U.S. Pat. No. 4,399,539 discloses a system for producing lasing in singly ionized atoms by using autoionization of an alkaline earth atom to create a population of singly ionized atoms in a metastable state. The ion is further pumped from the metastable state to a higher state by a tuneable laser. The Eden et al., U.S. Pat. No. 4,736,381 discloses a system for producing lasing in various molecules in the visible region of the spectrum through photodissociation of metal halides. The Suckewer U.S. Pat. No. 4,704,718 discloses a system in which highly ionized atoms are photopumped to excited states by multiphoton excitation from the ground state provided by light from a fixed-frequency picosecond-type laser. The excited state is then lased to lower states. Additionally, a review of short wavelength laser research is provided by Waynant et al., Proceedings of the IEEE, Vol. 64, No. 7 (July 1976), pages 1059-1092.
The use of coincident line pairs for photoexcitation pumping of short wavelength lasers was first proposed by Vinogradov et al., Sov. J. Quantum Electron, Vol. 5, No. 1, 59 (1975) and by Norton et al., J. Phys., B, Vol. 8, No. 6, 989 (1975). Generally, intense line radiation from one ion is used to selectively pump an upper level of another ion. A review of this method and a list of line matches for H-like, He-like, Li-like and other ions is provided by Dixon et al., J. Opt. Soc. Am., B, Vol. 1, No. 2, 232 (1984).
However, many laser systems which are known are disadvantageous in that they require complex apparatus and operating procedures and/or are economically unfavorable.